What browser(s) are you using?
Firefox and Google Chrome
What Operating System are you using?
What is the exact link to the page you are having a problem with?
The "Leave a comment for the moderators" parts on all editable wiki pages.
Details, details, details. Explain it in details.
Whenever I wiki edit, I often leave comments stating what was changed or added, but I can't write in anything at all whenever I click the section. The same thing's happening on Anime Vice, Giant Bomb and even Comic Vine.